Blade for a wind turbine and a method of assembling laminated profiles for a blade

ABSTRACT

The invention relates to a blade for use on a wind turbine and a method of assembling laminated profiles ( 3, 5 ) for a blade for a wind turbine. The development towards increasingly larger blades requires, that the technology of manufacture is reviewed and novel methods applied, in particular with regard to aspects regarding strength and weight. It is an object of the invention to provide a blade that can be manufactured more accurately and with large uniformity with regard to strength, from blade to blade, and which is lighter than prior art blades. Novel aspects of the invention regards that the wing comprises a beam part ( 2 ) which comprises at least a first part ( 4 ) and at least a second part ( 6 ), said first part ( 4 ) comprising at least one body part ( 12 ) connected to at least one assembly face ( 10 ) and to at least one abutment flange ( 14 ) said second part ( 6 ) comprising at least one body part ( 18 ) connected to at least one assembly face ( 16 ) and to at least one abutment flange ( 20 ); wherein the parts ( 4, 6 ) are adjusted by use of means for height adjustment ( 8 ) and connected to each other at the assembly faces ( 10, 16 ); and wherein the laminated profiles ( 3, 5 ) are assembled around the beam part ( 2 ) and glued against respective abutment flanges ( 14, 20 ). Hereby it is obtained that the height of the beam part can be adjusted in accordance with the thickness of the laminated profiles, such that the glued joint reaches the desired thickness, thereby an amount of glue is saved, since extra dosage is avoided, whereby the blade becomes less expensive and lighter.

The invention relates to a blade for use on a wind turbine, said bladebeing of the type that essentially comprises at least two separatelymanufactured fibre-reinforced laminated profiles and at least onelongitudinally extending beam portion. The invention also relates to amethod of assembling laminated profiles for a blade for a wind turbine.

Blade profiles/blades are already known that are built essentially fromtwo laminated profiles that are assembled by means of gluing, and insideof which there is located a carrier beam that can be one or more metalprofiles or a wound GRP profile onto which the laminated profiles arealso glued.

Those aides of the laminated profiles that are to be glued to thecarrier beam are constituted of hand-laid inner sides that are notmachined, for the sake of price and practicalities, and therefore theycomprise considerable inaccuracies. Furthermore a large number of mouldsare usually employed for the manufacture of the halves, said halvesbeing at a later point in time combined randomly, thereby furtherincreasing the inaccuracies. Therefore due regard is to be taken to theentire number of tolerances—both on moulds, thickness of laminatedprofiles and height of carrier beam. Thus, there is a risk that thelaminated profiles become thickest while simultaneously the carrier beamis highest.

In practice it is hence necessary to adapt the dimensions of the partsto the largest sum of tolerances, which means that usually there is alarge gap between the laminated profiles and the carrier beam. This gapis to be taken up by the glued joint, which is particularly critical inthose cases where the carrier beam is essentially to carry the forces asopposed to the laminated profiles carrying; and wherein the demands tothe strength of the glued joint are the highest. The strength andlongevity of the glued joint are moreover influenced by the thickness ofthe glued joint it is moreover a quality assurance aspect as the gluedjoint is concealed under the laminated profiles and hence difficult tocheck. In order to be sure that there is sufficient glue to fill thegap, it is necessary to dose an excess amount of glue, which increasesthe weight of the blade and is an additional cost, the glue being arelatively expensive resource, and thick glued joints have aconsiderably decreased strength and life. The larger the blades are, thelarger is the problem, which is unfortunate. The development towardsincreasingly large blades require that the technology of manufacture isreviewed and new methods applied, in particular with regard to aspectsrelating to strength and weight. When viewing a blade that can have alength of more than 30 m and a width of several meters, a gap of 15 mmdoes not seem important, but it may actually involve a large extraconsumption of glue, which constitutes a significant additional cost.Those 15 mm multiplied by the width of the carrier beam multiplied bythe length of the carrier beam yields a rather large volume. In case ofblades of 70 m the gap and the extra consumption of glue becomesextremely significant.

It is an object of the invention to provide a blade that can bemanufactured more accurately and with an increased uniformity withregard to strength from blade to blade compared to prior art blades. Itis a further object of the invention to achieve a blade constructionwhich is lighter and less expensive than prior art blades. Furtherobjects are to provide a method of assembling laminated profiles that ismore accurate than the prior art methods and which result in savings ofglue during assembly of the blade.

Novel and characterising aspects of the invention comprise that the beampart comprises at least one first part and at least one second part,said first part comprising at least one body part connected to at leastone assembly face and to at least one abutment flange, wherein the partsare adjusted with means for height adjustment and connected to eachother at the assembly faces, and wherein the laminated profiles areassembled around the beam part and glued to the respective abutmentflanges.

From the characterising aspects several advantages are obtained,including that the height of the bam part can be adapted to thethickness of the laminated profiles, such that the glued joint obtainsthe desired thickness. Hereby an amount of glue is saved, since extradosage is avoided, thereby making the blade less expensive and lighter.The beam part being at the beginning divided into at least two parts,these two parts are considerably less rigid than the final beam part.Thereby they are flexible enough to be adjusted differently along thebeam part, such that differences in thickness of the laminated profilesacross their length can also be absorbed. As a side effect it is alsoobtained that, when the blade becomes lighter, the load on the bearingof the blade becomes smaller.

Each of the parts may comprise two parallel body parts, which body partsare at their one end connected to an essentially transversally extendingabutment flange, and at their other end connected to a transversallyextending flange, which flanges comprise assembly faces. Hereby it isobtained that, when the parts are joined, they combine to form anessentially closed cross section that provides a high degree ofrigidity, including a high degree of bending and torsional stiffness.Due to the transversal flanges, it is further obtained that the assemblyfaces become wide and are readily assembled in a strong a durablemanner.

Means for height adjustment includes glue, which is appropriate in thosecases, where the gap has been reduced so much by care that the necessaryheight adjustment is considerably reduced.

Means for height adjustment includes eg screws, spacer elements,interlayers or the like, whereby it is easy and expedient to perform theadjustment and it can be done accurately. Besides, it is obtained thatthe adjustment can be performed differently over the length of the beampart.

The beam part may comprise at least one assembly panel that overlaps thebody parts and are connected to both parts. Thereby it pan be avoidedthat excess glue from the joint between the assembly faces enter andbecome located in beam part and adds superfluous weight. Besides, theassembly panel contributes to guide the parts towards each other duringtheir assembly. Moreover the assembly panel increases the strength ofthe assembly since the glue area is increased and glued portions areprovided which are able to be situated more or less perpendicular toeach other.

The assembly panel can be T-shaped thereby enabling it to simultaneouslyconstitute a spacer element for height adjustment between the assemblyfaces.

The invention also comprises a method of assembling laminated profilesfor a blade for a wind turbine, said blade being of the type thatessentially comprises at least two separately manufacturedfibre-reinforced laminated profiles and at least one longitudinallyextending beam part.

Novel and characterising aspects of the method comprises that the beampart comprises at least one first part and at least one second part,said first part comprising at least one body part connected to at leastone assembly face and to at least one abutment flange, said second partcomprising at least one body part connected to at least one assemblyface and to at least one abutment flange, where at least one of theparts is manufactured to be undersized, and where the total height ofthe parts is adjusted, after which the parts are connected, and wherethe laminated profiles are assembled around the beam part and gluedtowards the respective abutment flanges.

On the basis of the novel and characterising aspects of the invention itis obtained that the beam part can be adapted corresponding to theinternal dimension between the contour of the inner sides of thelaminated profiles, such that the glue joint between the laminatedprofiles and the respective abutment flanges becomes well-defined.Thereby glue is saved as extra dosage is avoided, thereby enablinglighter and less expensive blades and, likewise, the durability isimproved.

The parts can be connected by gluing, which is an advantageous assemblyprocedure.

The parts can be laid in moulds with the abutment flanges facing towardsthe mould walls. Thereby the contour of the abutment flanges become verywell-defined, which contributes to a strong and durable assembly withthe laminated profiles. In return, the assembly faces become lessaccurate, but they will be situated where the height adjustment takesplace, whereby the significance of the inaccuracy is more or lesseliminated.

Each of the parts may comprise two parallel body parts, said body partsbeing at their one end connected to an essentially transversallyextending abutment flange and, at its other end, it is connected to atransversally extending flange, said flanges comprising assembly faces,where, prior to assembly of the parts, two assembly panels are mounted,such that the assembly panels will, upon assembly of the parts, overlapthe body parts, said assembly panels being connected to both parts.Thereby the assembly panels are caused to constitute structural elementsin the beam part and the strength is increased. Besides, it becomeseasier to control gluing of the assembly faces, as the assembly panelsprevent excess glue from running into the beam part. Additionally, itbecomes easier to guide the parts to their place in relation to eachother, which is a relief in particular in case of very long beam partsfor large blades.

The joints are preferably performed by gluing and subsequent hardening.

In the following, the invention will be described in further detail andexemplary embodiments will appear from the figures, wherein

FIG. 1 is a cross sectional view of a blade for a wind turbine;

FIG. 2 shows two laminated profiles in cross sectional view;

FIG. 3 is a cross sectional view of beam part in exploded view;

FIG. 4 is a partial view of a cross section of a beam part;

FIG. 5 is a partial view of a cross section of a beam part;

FIG. 6 is a cross sectional view of a beam part;

FIG. 7 is a cross sectional view of a beam part;

FIG. 8 is a partial view of a cross section of a beam part; and

FIG. 9 is a partial view of a cross section of a beam part.

FIG. 1 shows a simplified cross sectional view of a blade for a windturbine comprising two laminated profiles 3 and 5 that constitutes theaerodynamically active part of the blade within the blade is located abeam part 2 comprising a first part 4 and a second a second part 6. Thetotal height of the beam part 2 can be adjusted by means for heightadjustment 8. The laminated profiles 3 and 5 are connected to the beampart 2, preferably by gluing.

FIG. 2 shows two laminated profiles 3 and 5 located in the position theyare constructed for being located in. The laminated profiles 3 and 5 aremanufactured by manually laying a fibre material and a binder, egpolyester or epoxy, in a mould whereby the outer side of the laminatedprofiles, cf. the in-use situation, faces towards the mould. Hereby themost accurate external contour is achieved, which is important to theyield of the wind turbine. The internal side of the laminated profilesis far from permanently defined as this is rendered impossible bydifferences and variation in ia the fibre material. Thereby thethickness is caused to vary considerably and consequently the dimensiondesignated D in FIG. 2 will also vary. In the prior ar where a carrierbeam is used of either and for example metal profiles or a wound GRPbeam the amount of glue necessary for reaching from the inner side ofthe laminated profiles and to the carrier beam will differ because Dvaries. Thereby the thickness of the glue joint will vary. This meansthat, in many cases, a large amount of glue will be used, eg because thecarrier beam can be considerably lower in height than D. The gap betweenthe laminated profile and the beam is to be taken up by the glued joint,which is particularly critical in those cases where the carrier beam isessentially to carry the forces, as opposed to the laminated profilescarrying, and wherein the requirements to the strength of the gluedjoint are the highest. The strength and life of the glue joint are alsoinfluenced by the thickness of the glued joint.

FIG. 3 shows an exploded view of a cross section of a beam part 2. Thebeam part 2 comprises at east a first part 4, at least a second part 6,and means for height adjustment 8, which first part 4 comprises at leastone body portion 12 connected to at least one assembly face 10 and to atleast one abutment flange 14, which second part 6 comprises at least onebody portion 18 connected to at least one assembly face 16 and to atleast one abutment flange 2 wherein the parts 4 and 6 are, at theassembly faces 10 and 16, adjustable by means of means for heightadjustment 8. In the embodiment shown in FIG. 3, a first part 4comprises two body parts 12 a and 12 b and is, at its first end,connected to a transversal abutment flange 14, and at the other endconnected to transversal flanges 22 a and 22 b. On the side of the part4 facing towards the second part 6, is located two assembly faces 10 aand 10 b. The assembly faces are located on the transversal flanges 22 aand 22 b. The second part 6 comprises two body parts 18 a and 18 b andis, at its one end connected to a transversal abutment flange 20 and, atthe other end, it is connected to transversal flanges 24 a and 24 b. Onthe side of the part 6 that faces towards the first part 4, two assemblyfaces 16 a and 16 b are located. The assembly faces are located on thetransversal flanges 24 a and 24 b. The parts 4 and 6 are preferablymanufactured by laying up of fibre material and binder in moulds, wherethe abutment flanges 14 and 20 face towards the moulds. FIG. 3 showsmeans for height adjustment 8 shows as intermediate-layer plates. With anumber of intermediate-layer plates of varying thickness, it is possibleto adjust the distance until the beam part 2 reaches a heightcorresponding to the interior distance between two current laminatedprofiles, see FIGS. 1 and 2. In case of parts 4 and 6 that are notprovided with transversal flanges 22 a, 22 b, 24 a and 24 b the assemblyfaces 10 and 16 will eg be the end of the body parts 12 and 18 that arenot connected to the abutment flanges 14 and 20. In case of bladeconstructions, where the beam part 2 is to constitute an essential partof the strength and rigidity, the thickness of the abutment flanges 14and 20 may be considerably larger than the thickness of body parts 12and 18.

FIG. 4 shows a beam part 2 with two parts 4 and 6 that comprisetransversal flanges 22 a and 24 a. Also shown are means for heightadjustment 8 that comprise screws 32, which eg is placed in a nut (notshown) that may be embedded in the transversal flange 22 a. Adjustmentof the height of the beam part 2 can be achieved by adjusting the screw32 that support/press on the flange 24 a. When the desired height hasbeen reached, for instance the first part 4 can be lifted upwards andclear of the other part 6, such that it is possible to apply glue forassembling the parts 4 and 6. Alternatively the interface between theparts 4 and 6 can be closed with fibre material and binder.

FIG. 5 shows yet another embodiment of means for height adjustment 8,wherein blocks 30 are secured on the side of the first part 4 and theside of the second part 6, and of which the uppermost block is providedwith thread, in which thread a threaded bar 30 is provided by which itis possible to adjust the distance between the parts 4 and 6 and hencethe height of the beam part 2.

FIG. 6 shows a beam part 2, where the bending stiffness is increased byinsertion of an additional layer 34 of fibre material and binderinternally on the abutment flanges 14 and 20. In this manner therigidity can be increased in a simple manner, eg in case the blade is tobe used under increased requirements to use. Moreover, the figures showsthat the transversal flanges 22 and 24 can also face towards each other.

FIG. 7 shows a beam part 2 that comprises four parts 4 a, 4 b, 6 a and 6b. The parts 4 a and 4 b and 6 a and 6 b, respectively can be joinedseparately in pairs. Alternatively the pairs 4 a and b and 6 a and 6 bcould be manufactured in one piece.

FIGS. 8 and 9 show sections of a beam part 2, where an assemply panel 26is mounted. In FIG. 8 the assembly panel 26 is mounted on the body part18 a and cover the gap between the two parts 4 and 6. There ispreferably a thin gap between the assembly panel 26 and the body part 12a, such that, during assembly of the parts 4 and 6, glue is also appliedto the side of the assembly panel 26, which is thus secured on bothparts and contributes to the strength. The distance between the parts 4and 6 is suitable for means 8 for height adjustment to be constituted byglue 38. The assembly panel 26 moreover sees to it that excess glue doesnot run into and become deposited within the beam part 2. FIG. 9 shows aT-shaped assembly panel 26 wherein the strengthening function and theglue-stopping function are achieved in combination with aheight-adjusting function, the one arm acting as intermediate layer. Ofcourse, it is possible to use a number of T-shaped assembly panels ofvarious thickness for the sake of the height-adjusting function.

1. A blade for use on a wind turbine, said blade being of the type thatessentially comprises at least two separately manufactured,fibre-reinforced laminated profiles (3, 5) and at least onelongitudinally extending beam part (2), wherein the beam part (2)comprises at least one first part (4) and at least on second part (6),said first part (4) comprising at least one body part (12) connected toat least one assembly face (10) and at least one abutment flange (14),said second part (6) comprising at least one body part (18) connected toat least one assembly face (16) and to at least one abutment flange(20), wherein the parts (4, 6) are adjusted by means for heightadjustment (8) and connected to each other at the assembly faces (10,16), and wherein the laminated profiles (3, 5) are assembled around thebeam part (2) and glued against respective abutment flanges (14, 20). 2.A blade according to claim 1, wherein each of the parts (4, 6) comprisetwo parallel body parts (12 a, 12 b, 18 a, 18 b), said body parts beingat their one end connected to an essentially transversally extendingabutment flange (14, 20) and at their other end connected to atransversally extending flange (22 a, 22 b, 24 a, 24 b), said flangescomprising assembly faces (10 a, 10 b, 16 a, 16 b).
 3. A blade accordingto claim 1, wherein the means for height adjustment (8) comprises glue.4. A blade according to claim 1, wherein the means for height adjustment(8) comprises screws, space elements, intermediate layers, or the like.5. A blade according to claim 1, wherein the beam part (2) comprises atleast one assembly panel (26) that overlaps the body parts (12, 18) andare connected to both parts (4, 6).
 6. A blade according to claim 4,wherein the assembly panel (26) is T-shaped.
 7. A method of assemblinglaminated profiles for a blade for a wind turbine, said blade being ofthe type that comprises at least two separately manufactured,fibre-reinforced laminated profiles (3, 5) and at least onelongitudinally extending beam part (2), wherein the beam part (2)comprises at least a first part (4) and at least a second part (6), saidfirst part (4) comprising at least one body part (12) connected to atleast one assembly face (10) and at least one abutment flange (14), saidsecond part (6) comprising at least one body part (18) connected to atleast one assembly face (16) and to at least one abutment flange (20),wherein the method comprises the following steps: manufacturing at leastone of the parts (4, 6) to be undersized; adjusting the total height ofthe parts (4, 6); connecting the parts (4, 6); and assembling thelaminated profiles (3, 5) around the beam part (2) and glued to therespective abutment flanges (14, 20).
 8. A method according to claim 7,wherein the parts (4, 6) are connected by gluing.
 9. A method accordingto claim 7, wherein the parts (4, 6) are laid in moulds with theabutment flanges (14, 20) facing the mould walls.
 10. A method accordingto any on of claims 4 claim 7, wherein each of the parts (4, 6)comprises two parallel body parts (12 a, 12 b, 18 a, 18 b), said bodyparts being at their one end connected to an essentially transversallyextending abutment flange (14, 20) and at their other end connected to atransversally extending flange (22 a, 22 b, 24 a, 24 b), said flangescomprising assembly faces (10 a, 11 b, 16 a, 16 b), wherein prior toassembly of the parts (4, 6) in the assembly step, two assembly panels(26) are mounted, such that the assembly panels will, upon assembly ofthe parts, overlap the body parts (12 a, 12 b, 18 a, 18 b), saidassembly panels (26) being connected to both parts (4, 6).